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Solution-processed upconversion photodetectors based on quantum dots


Upconversion photodetectors convert photons from the infrared to the visible light spectrum and are of use in applications such as infrared detection and imaging. High-performance upconversion devices are, however, typically based on vacuum-deposited materials, which are expensive and require high operating voltages, which limits their implementation in flexible systems. Here we report solution-processed optical upconversion photodetectors with a high photon-to-photon conversion efficiency of 6.5% and a low turn-on voltage of 2.5 V. Our devices consist of a colloidal lead sulfide quantum dot layer for harvesting infrared light that is monolithically coupled to a cadmium selenide/zinc selenide quantum dot layer for visible-light emission. We optimized the charge-extraction layers in these devices by incorporating silver nanoparticles into the electron transport layers to enable carrier tunnelling. Our photodetectors exhibit a low dark current, high detectivity (6.4 × 1012 Jones) and millisecond response time, and are compatible with flexible substrates. We also show that the devices can be used for in vitro bioimaging.

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Fig. 1: Infrared imaging using flexible upconversion devices.
Fig. 2: Structure and composition of upconversion devices herein.
Fig. 3: Operation of the photodetector.
Fig. 4: Characterization of solution-processed upconversion devices.
Fig. 5: Applications of solution-processed upconversion devices.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.


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We acknowledge financial support from the National Key Research and Development Program of China (under Grant no. 2016YFA0204000), National Natural Science Foundation of China (61935016, U1632118 and 21571129), Shanghai Tech start-up funding, 1000 Young Talent program and the Science and Technology Commission of Shanghai Municipality (16JC1402100 and 16520720700). We thank the support from Analytical Instrumentation Center (#SPST-AIC10112914), SPST, ShanghaiTech University. We thank X. Wang at Alberta University for helpful discussions. We also thank B. Chen and his group members for their help of measuing the noise of photodetector.

Author information




W.Z. and Z.N. conceived the idea and designed the experiments. K.X., R.W. and Y.S. synthesized the QDs. W.Z., S.L., X.X. and Y.S. fabricated and measured the devices. W.Z. performed theoretical modelling. X.Z. and R.H. performed the tumour growth in mice experiments. W.Z. and F.P.G.A. carried out the data analysis. W.Z., Z.N., F.P.G.A. and E.H.S. co-wrote the manuscript. All the authors contributed to the editing of the manuscript.

Corresponding author

Correspondence to Zhijun Ning.

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Extended data

Extended Data Fig. 1 Characterization of Ag nanoparticles in ZnO films.

Characterization of Ag nanoparticles in ZnO films. (a) SEM image of the ZnO surface. (b)EDS elemental mapping images of the cross section of the ZnO films with Ag nanoparticles for Ag element. (c) EDS elemental mapping images of the cross section of the ZnO films with Ag nanoparticles for Zn element. (d) EDS elemental mapping images of the cross section of the ZnO films with Ag nanoparticles for O element.

Extended Data Fig. 2 Comparison of the performance of the photodetectors.

Comparison of the performance of the photodetectors.

Supplementary information

Supplementary Information

Supplementary Figs. 1–17 and Table 1.

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Zhou, W., Shang, Y., García de Arquer, F.P. et al. Solution-processed upconversion photodetectors based on quantum dots. Nat Electron 3, 251–258 (2020).

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